This invention relates to a novel method of fortifying foods or animal feeds with a source of methionine.
Certain amino acids are indispensable components of the diet of higher animals and are called essential amino acids. It has been shown that for maintenance of nitrogen balance, a certain fixed level of the essential amino acids must be supplied in the diet. If just one of these amino acids is not at the required level, then the animal fails to grow at an optimum rate, regardless of the fact that the other essential amino acids are in adequate or in more than adequate supply. The acid in short supply is termed "limiting".
This problem has been encountered, for example, in the poultry industry, where rations are designed for optimum performance at least cost. In the typical corn-soybean meal rations, methionine is the first limiting amino acid because the content of this amino acid tends to be lower in terms of the concentration of the other essential amino acids. While methionine is an essential amino acid, it must be obtained from outside sources because it cannot be synthesized in the organism of a higher animal.
Commercial livestock feeds are mainly mixtures of various grains, grain and mill by-products, oil meals, roughages, etc., very little animal protein being used. Because of this fact, the rations tend to be marginal or limiting in terms of methionine for optimum growth performance, since the methionine content of plant protein is relatively low. Supplementation of poultry foods with low levels of methionine results in marked increases of meat production and feed efficiency. Supplementation of feeds for poultry, pigs, sheep, beef and dairy animals should result in improved meat and milk production.
Likewise, methionine can be limiting in human diets in areas of the world where the dietary protein is mainly of vegetable origin. In such areas, supplementation of the human diet with methionine or an acceptable methionine source would improve the nutritional status of local populations.
Methionine suffers from a serious shortcoming in that it develops on standing an unpleasant odor, which can adversely affect the palatability of foods or feeds fortified therewith. An ideal fortifying agent would be an odor-free methionine source from which methionine could be readily recovered in the animal or human organism.